Aqueous urethane resin compositions produced by dispersing a urethane resin in an aqueous medium have been widely used as a material of leather-like sheets such as artificial leather and synthetic leather, coating agents, adhesives, or the like, because the aqueous urethane resin compositions cause a smaller environmental load than the organic-solvent-based urethane resin compositions of the related art.
In general, most of the leather-like sheets are constituted by a base composed of nonwoven fabric or the like, an intermediate layer including a porous layer, and a surface coating layer, and the base is produced by impregnating a fiber base composed of nonwoven fabric or the like with an aqueous urethane resin composition and subsequently performing thermal coagulation of the urethane resin composition in order to enhance the flex resistance and feeling of the leather-like sheets.
As an aqueous urethane resin composition with which the fiber base is impregnated, for example, there has been proposed a urethane resin composition including a urethane resin, a nonionic emulsifier, and an aqueous medium, the urethane resin being produced by reacting a polyol including a polyol including a carboxyl group with an alicyclic polyisocyanate and a chain extender including an amino group (see, e.g., PTL 1).
However, this aqueous urethane resin composition is likely to become discolored with time. Furthermore, goods produced using the aqueous urethane resin composition are paper-like and do not have resilience. Thus, the improvement of the feeling of goods produced using the aqueous urethane resin composition has been needed.